Increased incidence of lobular breast cancer in women treated with hormone replacement therapy: implications for diagnosis, surgical and medical treatment.

A growing body of evidence support the association between the use of hormone replacement therapy (HRT) and a higher risk of both invasive lobular carcinoma (ILC) and invasive ductal-lobular mixed carcinoma (IDLC). Overall biological and clinical features of ILC entail a more cautious diagnostic and therapeutic approach as compared with invasive ductal carcinoma (IDC). ILCs are more frequently multifocal, multicentric and/or bilateral. Mammography and ultrasound show, therefore, significant limitations, while the higher sensitivity of magnetic resonance imaging in the detection of multifocal and/or multicentric lesions seems to improve the accuracy of preoperative staging of ILCs. Early diagnosis is even more challenging because the difficult in the localization and the sparse cellularity of lobular tumours may determine a false negative core biopsy. ILC is characterized by low proliferative activity, C-ErbB-2 negativity, bcl-2 positivity, p53 and VEGF negativity, oestrogen and progesterone positive receptors, low grade and low likelihood of lymphatic-vascular invasion. However, this more favourable biological behaviour does not reflect into a better disease-free and overall survival as compared with IDC. Since lobular histology is associated with a higher risk of positive margins, mastectomy is often preferred to breast conservative surgery. Moreover, only few patients with ILC achieve a pathologic response to preoperative chemotherapy and, therefore, in most patients mastectomy can be regarded as the safer surgical treatment. The preoperative staging and the follow-up of patients with ILC are also complicated by the particular metastatic pattern of such histotype. In fact, metastases are more frequently distributed to the gastrointestinal tract, peritoneum/retroperitoneum and gynaecological organs than in IDC.